/***************************************************************************************[SimpSolver.h]
 Glucose -- Copyright (c) 2009-2014, Gilles Audemard, Laurent Simon
								CRIL - Univ. Artois, France
								LRI  - Univ. Paris Sud, France (2009-2013)
								Labri - Univ. Bordeaux, France

 Syrup (Glucose Parallel) -- Copyright (c) 2013-2014, Gilles Audemard, Laurent Simon
								CRIL - Univ. Artois, France
								Labri - Univ. Bordeaux, France

Glucose sources are based on MiniSat (see below MiniSat copyrights). Permissions and copyrights of
Glucose (sources until 2013, Glucose 3.0, single core) are exactly the same as Minisat on which it
is based on. (see below).

Glucose-Syrup sources are based on another copyright. Permissions and copyrights for the parallel
version of Glucose-Syrup (the "Software") are granted, free of charge, to deal with the Software
without restriction, including the rights to use, copy, modify, merge, publish, distribute,
sublicence, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

- The above and below copyrights notices and this permission notice shall be included in all
copies or substantial portions of the Software;
- The parallel version of Glucose (all files modified since Glucose 3.0 releases, 2013) cannot
be used in any competitive event (sat competitions/evaluations) without the express permission of
the authors (Gilles Audemard / Laurent Simon). This is also the case for any competitive event
using Glucose Parallel as an embedded SAT engine (single core or not).


--------------- Original Minisat Copyrights

Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Copyright (c) 2007-2010, Niklas Sorensson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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 **************************************************************************************************/

#ifndef Glucose_SimpSolver_h
#define Glucose_SimpSolver_h

#include "core/Solver.h"
#include "mtl/Clone.h"
#include "mtl/Queue.h"

namespace Glucose {

//=================================================================================================

class SimpSolver : public Solver
{
  public:
	// Constructor/Destructor:
	//
	SimpSolver();
	~SimpSolver();

	SimpSolver(const SimpSolver& s);

	/**
	 * Clone function
	 */
	virtual Clone* clone() const { return new SimpSolver(*this); }

	// Problem specification:
	//
	virtual Var newVar(bool polarity = true,
					   bool dvar = true); // Add a new variable with parameters specifying variable mode.
	bool addClause(const vec<Lit>& ps);
	bool addEmptyClause();				 // Add the empty clause to the solver.
	bool addClause(Lit p);				 // Add a unit clause to the solver.
	bool addClause(Lit p, Lit q);		 // Add a binary clause to the solver.
	bool addClause(Lit p, Lit q, Lit r); // Add a ternary clause to the solver.
	virtual bool addClause_(vec<Lit>& ps);
	bool substitute(Var v, Lit x); // Replace all occurences of v with x (may cause a contradiction).

	// Variable mode:
	//
	void setFrozen(Var v, bool b); // If a variable is frozen it will not be eliminated.
	bool isEliminated(Var v) const;

	// Solving:
	//
	bool solve(const vec<Lit>& assumps, bool do_simp = true, bool turn_off_simp = false);
	lbool solveLimited(const vec<Lit>& assumps, bool do_simp = true, bool turn_off_simp = false);
	bool solve(bool do_simp = true, bool turn_off_simp = false);
	bool solve(Lit p, bool do_simp = true, bool turn_off_simp = false);
	bool solve(Lit p, Lit q, bool do_simp = true, bool turn_off_simp = false);
	bool solve(Lit p, Lit q, Lit r, bool do_simp = true, bool turn_off_simp = false);
	bool eliminate(bool turn_off_elim = false); // Perform variable elimination based simplification.

	// Memory managment:
	//
	virtual void garbageCollect();

	// Generate a (possibly simplified) DIMACS file:
	//
#if 0
    void    toDimacs  (const char* file, const vec<Lit>& assumps);
    void    toDimacs  (const char* file);
    void    toDimacs  (const char* file, Lit p);
    void    toDimacs  (const char* file, Lit p, Lit q);
    void    toDimacs  (const char* file, Lit p, Lit q, Lit r);
#endif

	// Mode of operation:
	//
	int parsing;
	int grow;			 // Allow a variable elimination step to grow by a number of clauses (default to zero).
	int clause_lim;		 // Variables are not eliminated if it produces a resolvent with a length above this limit.
						 // -1 means no limit.
	int subsumption_lim; // Do not check if subsumption against a clause larger than this. -1 means no limit.
	double
		simp_garbage_frac; // A different limit for when to issue a GC during simplification (Also see 'garbage_frac').

	bool use_asymm;	 // Shrink clauses by asymmetric branching.
	bool use_rcheck; // Check if a clause is already implied. Prett costly, and subsumes subsumptions :)
	bool use_elim;	 // Perform variable elimination.
	// Statistics:
	//
	int merges;
	int asymm_lits;
	int eliminated_vars;

  protected:
	// Helper structures:
	//
	struct ElimLt
	{
		const vec<int>& n_occ;
		explicit ElimLt(const vec<int>& no)
			: n_occ(no)
		{
		}

		// TODO: are 64-bit operations here noticably bad on 32-bit platforms? Could use a saturating
		// 32-bit implementation instead then, but this will have to do for now.
		uint64_t cost(Var x) const { return (uint64_t)n_occ[toInt(mkLit(x))] * (uint64_t)n_occ[toInt(~mkLit(x))]; }
		bool operator()(Var x, Var y) const { return cost(x) < cost(y); }

		// TODO: investigate this order alternative more.
		// bool operator()(Var x, Var y) const {
		//     int c_x = cost(x);
		//     int c_y = cost(y);
		//     return c_x < c_y || c_x == c_y && x < y; }
	};

	struct ClauseDeleted
	{
		const ClauseAllocator& ca;
		explicit ClauseDeleted(const ClauseAllocator& _ca)
			: ca(_ca)
		{
		}
		bool operator()(const CRef& cr) const { return ca[cr].mark() == 1; }
	};

	// Solver state:
	//
	int elimorder;
	bool use_simplification;
	vec<uint32_t> elimclauses;
	vec<char> touched;
	OccLists<Var, vec<CRef>, ClauseDeleted> occurs;
	vec<int> n_occ;
	Heap<ElimLt> elim_heap;
	Queue<CRef> subsumption_queue;
	vec<char> frozen;
	vec<char> eliminated;
	int bwdsub_assigns;
	int n_touched;

	// Temporaries:
	//
	CRef bwdsub_tmpunit;

	// Main internal methods:
	//
	virtual lbool solve_(bool do_simp = true, bool turn_off_simp = false);
	bool asymm(Var v, CRef cr);
	bool asymmVar(Var v);
	void updateElimHeap(Var v);
	void gatherTouchedClauses();
	bool merge(const Clause& _ps, const Clause& _qs, Var v, vec<Lit>& out_clause);
	bool merge(const Clause& _ps, const Clause& _qs, Var v, int& size);
	bool backwardSubsumptionCheck(bool verbose = false);
	bool eliminateVar(Var v);
	void extendModel();

	void removeClause(CRef cr, bool inPurgatory = false);
	bool strengthenClause(CRef cr, Lit l);
	void cleanUpClauses();
	bool implied(const vec<Lit>& c);
	virtual void relocAll(ClauseAllocator& to);
};

//=================================================================================================
// Implementation of inline methods:

inline bool
SimpSolver::isEliminated(Var v) const
{
	return eliminated[v];
}
inline void
SimpSolver::updateElimHeap(Var v)
{
	assert(use_simplification);
	// if (!frozen[v] && !isEliminated(v) && value(v) == l_Undef)
	if (elim_heap.inHeap(v) || (!frozen[v] && !isEliminated(v) && value(v) == l_Undef))
		elim_heap.update(v);
}

inline bool
SimpSolver::addClause(const vec<Lit>& ps)
{
	ps.copyTo(add_tmp);
	return addClause_(add_tmp);
}
inline bool
SimpSolver::addEmptyClause()
{
	add_tmp.clear();
	return addClause_(add_tmp);
}
inline bool
SimpSolver::addClause(Lit p)
{
	add_tmp.clear();
	add_tmp.push(p);
	return addClause_(add_tmp);
}
inline bool
SimpSolver::addClause(Lit p, Lit q)
{
	add_tmp.clear();
	add_tmp.push(p);
	add_tmp.push(q);
	return addClause_(add_tmp);
}
inline bool
SimpSolver::addClause(Lit p, Lit q, Lit r)
{
	add_tmp.clear();
	add_tmp.push(p);
	add_tmp.push(q);
	add_tmp.push(r);
	return addClause_(add_tmp);
}
inline void
SimpSolver::setFrozen(Var v, bool b)
{
	frozen[v] = (char)b;
	if (use_simplification && !b) {
		updateElimHeap(v);
	}
}

inline bool
SimpSolver::solve(bool do_simp, bool turn_off_simp)
{
	budgetOff();
	assumptions.clear();
	return solve_(do_simp, turn_off_simp) == l_True;
}
inline bool
SimpSolver::solve(Lit p, bool do_simp, bool turn_off_simp)
{
	budgetOff();
	assumptions.clear();
	assumptions.push(p);
	return solve_(do_simp, turn_off_simp) == l_True;
}
inline bool
SimpSolver::solve(Lit p, Lit q, bool do_simp, bool turn_off_simp)
{
	budgetOff();
	assumptions.clear();
	assumptions.push(p);
	assumptions.push(q);
	return solve_(do_simp, turn_off_simp) == l_True;
}
inline bool
SimpSolver::solve(Lit p, Lit q, Lit r, bool do_simp, bool turn_off_simp)
{
	budgetOff();
	assumptions.clear();
	assumptions.push(p);
	assumptions.push(q);
	assumptions.push(r);
	return solve_(do_simp, turn_off_simp) == l_True;
}
inline bool
SimpSolver::solve(const vec<Lit>& assumps, bool do_simp, bool turn_off_simp)
{
	budgetOff();
	assumps.copyTo(assumptions);
	return solve_(do_simp, turn_off_simp) == l_True;
}

inline lbool
SimpSolver::solveLimited(const vec<Lit>& assumps, bool do_simp, bool turn_off_simp)
{
	assumps.copyTo(assumptions);
	return solve_(do_simp, turn_off_simp);
}

//=================================================================================================
}

#endif
